WO2014014305A1

WO2014014305A1 - Method and apparatus for selectively performing packet error classification of multiple packet streams multiplexed to same port

Info

Publication number: WO2014014305A1
Application number: PCT/KR2013/006479
Authority: WO
Inventors: 배성준; 이현우; 류원
Original assignee: 한국전자통신연구원
Priority date: 2012-07-19
Filing date: 2013-07-19
Publication date: 2014-01-23

Abstract

The present invention relates to a method and an apparatus for selectively performing packet error classification of multiple packet streams multiplexed to the same port. The method for generating an MMT packet according to the present invention comprises: a step of encapsulating an AU provided from a media codec layer to generate an MPU; and a step of packetizing the generated MPU to generate an MMT packet. The MMT packet has a packet header including a substream sequence number. According to the present invention, multiple substreams are multiplexed and transmitted to a single port, and it is possible to detect, if a packet loss occurs, to which substream the lost packet belongs. Furthermore, based on this, an automatic repeat request (ARQ) can be made differently for each subframe and an error control policy can be taken differently for each subframe.

Description

Method and apparatus for selectively performing packet error classification of multiple packet streams multiplexed on the same port

The present invention relates to a method and apparatus for performing packet error classification of multiple packet streams, and more particularly, to a method and apparatus for selectively performing packet error classification of multiple packet streams multiplexed on the same port.

Since the standardization of MPEG-2, the video compression standard (or audio compression standard) has been steadily developing new standards over the past decade: MPEG-4, H.264 / AVC, Scalable Video Coding (SVC). In addition, each new standard has expanded the scope of use of the MPEG standard by forming a new market, but in the case of transport technologies such as the MPEG-2 Transport System (TS), the digital and mobile broadcasts have remained unchanged for almost 20 years. It is widely used in T-DMB, DVB-H, etc., and even in multimedia transmission over the Internet, that is, IPTV service, which was not considered at the time of standard establishment.

However, when the MPEG-2 TS is developed, the multimedia transmission environment and today's multimedia transmission environment are undergoing major changes. For example, the MPEG-2 TS standard was developed in consideration of transmitting multimedia data through an ATM network at the time of enactment, but it is hard to find a case which is used for this purpose today. In addition, since the requirements such as multimedia transmission using the Internet were not considered at the time of enactment of the MPEG-2 TS standard, there are elements that are not efficient for multimedia transmission over the recent Internet. Accordingly, MPEG MMT (MPEG Media Transport), which is a new multimedia transmission standard, is enacted in consideration of the changing multimedia environment.

According to a media transmission scheme, several packet streams may be multiplexed in a substream form and transmitted to one port. However, when packet loss occurs, there is a problem in which substream before the lost packet is originally multiplexed cannot be identified.

Therefore, in consideration of the new media transmission environment and standards, a new media transmission technology for selectively performing packet error classification of multiple packet streams multiplexed on the same port is required.

An object of the present invention is to provide a method and apparatus for selectively performing packet error classification of multiple packet streams multiplexed on the same port.

Another technical problem of the present invention is to provide information regarding which substream a lost packet belongs to when a packet loss occurs.

Another technical problem of the present invention is to provide a method and apparatus for selectively distinguishing multiplexed multiple packet streams.

Another technical problem of the present invention is to efficiently separate multiplexed multiple packet streams so that an individual error control policy can be taken.

According to an aspect of the present invention, there is provided an apparatus for generating MPEG Media Transport (MMT) packets. The apparatus for generating MMT packets includes an encapsulation unit for generating an MPU by encapsulating an AU provided from a media codec layer, and a packetizing unit for generating an MMT packet by packetizing the generated MPU, wherein the packetization unit includes a substream sequence number. And generating the MMT packet having a packet header including a.

According to another aspect of the present invention, an MMT packet generation method by an MMT packet generation apparatus is provided. The MMT packet generating method includes generating an MPU by encapsulating an AU provided from a media codec layer, and generating an MMT packet by packetizing the generated MPU, wherein the MMT packet includes a substream sequence number. It is characterized by having a packet header.

According to another aspect of the present invention, in a system for generating an MMT packet, a header structure of an MMT packet is provided. The header structure of the MMT packet basically includes a substream ID field and a substream sequence number field, and further includes a general sequence number flag field indicating whether a general sequence number field exists.

According to the present invention, a plurality of substreams are multiplexed and transmitted to one port, and even when a packet loss occurs, it is possible to determine which substream the lost packet belongs to. Also, based on this, different ARQs and error control policies may be taken for each subframe.

1 is a conceptual diagram illustrating an MMT hierarchical structure.

2 is a flowchart illustrating a process of generating an MMT packet according to an embodiment of the present invention.

3 to 4 illustrate the concept of the substream_seqno field and the generic_seqno field and the usage examples of the substream_seqno field described above.

5 is a block diagram illustrating an apparatus for generating an MMT packet according to the present invention.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, terms such as "... unit" described in the specification means a unit for processing at least one function or operation, which may be implemented in hardware or software or a combination of hardware and software.

1 is a conceptual diagram illustrating an MMT hierarchical structure.

The MPEG Media Transport (MMT) layer includes an encapsulation layer, a delivery layer, and a signaling layer.

The encapsulation layer (E-layer) is a layer for packaging media data in a form that is friendly to both the transmission application in the IP network and the application for file storage. As shown in FIG. 1, the encapsulation layer includes an MMT E.1 layer, an MMT E.2 layer, and an MMT E.3 layer. Can be configured.

The MMT E.3 layer encapsulates an Access Unit (AU) provided from the Media Codec (A) layer to create a Media Processing Unit (MPU). The AU is the smallest unit of media data entity and may have timing information as an attribute. Here, the timing information may include a composition time stamp (CTS), a decoding time stamp (DTS), and the like, as information related to time among pieces of information required to consume each media data.

The composition time stamp (CTS) refers to the time when the corresponding access unit is displayed on the screen, and the decoding time stamp (DTS) refers to the time spent by the corresponding access unit in the decoder. One MPU may include one or more AUs.

The MMT E.2 layer encapsulates the MPU generated in the MMT E.3 layer to generate an MMT asset. The MMT asset is a data entity consisting of one or more MPUs, multiplexed by the MMT payload format and transmitted by the MMT protocol. The MMT payload format is a format for payload of an MMT package or MMT signaling message to be delivered by the MMT protocol or an Internet Application Layer protocol (eg, RTP). The MMT asset may correspond to a packetized elementary stream (PES) of MPEG-2 TS, and may include, for example, video, audio, program information, MPEG-U widgets, JPEG images, and MPEG 4 file formats. File Format), M2TS (MPEG Transport Stream), etc.

The MMT E.1 layer generates an MMT package by encapsulating the MMT asset generated in the MMT E.2 layer. The MMT package may be composed of one or a plurality of MMT assets together with additional information such as composition information and transport characteristics. The composition information may include information about a relationship between MMT assets, and may further include information for indicating a relationship between a plurality of MMT packages when one content includes a plurality of MMT packages. . The transport characteristics may include transmission characteristic information necessary for determining a delivery condition of an MMT asset or an MMT packet, and may include, for example, a traffic description parameter and a QoS descriptor. ) May be included. The MMT package may correspond to a program of MPEG-2 TS.

On the other hand, the transport layer (D-layer) is composed of MMT D.1 Layer (MMT D.1 Layer), MMT D.2 Layer (MMT D.2 Layer) and MMT D.3 Layer (MMT D.3 Layer) Can be.

The MMT D.1 layer receives the MMT package generated in the MMT E.1 layer and generates an MMT Payload format. The MMT payload format is a payload format for transmitting MMT assets and for transmitting information for consumption by the MMT application protocol or other existing application transmission protocol such as RTP.

The MMT D.2 layer receives an MMT payload format generated in the MMT D.1 layer and generates an MMT transport packet or an MMT packet. The MMT transport packet or MMT packet is a data format used in an application transport protocol for MMT.

The MMT D.3 layer (D.3-layer) supports the Quality of Service (QoS) by providing the function of exchanging information between layers by a cross-layer design. For example, the D.3 layer may perform QoS control using QoS parameters of the MAC / PHY layer.

On the other hand, the signaling layer (S layer) performs a signaling function (signaling function). For example, the signaling layer may include session initialization / control / management, server-based and / or client-based trick modes, service discovery, synchronization, and the like of transmitted media. It can perform a signaling function for.

As illustrated in FIG. 1, the signaling layer may include an MMT S.1 layer and an MMT S.2 layer.

The MMT S.1 layer interfaces with service discovery, media session initialization / termination of media, media session presentation / control of media, delivery layer and encapsulation layer. And the like.

The MMT S.2 layer relates to flow control, delivery session management, delivery session monitoring, error control, and hybrid network synchronization control. It is possible to define the format of the control message exchanged between delivery end-points of the delivery layer. In addition, the MMT S.2 layer may provide signaling required between a sender and a receiver to support the operation of the transport layer. In addition, the S.2 layer may be responsible for interfacing with the transport layer and the encapsulation layer.

The MMT packet generating apparatus according to the present invention generates the MMT packet according to the above-described definition of the MMT layer. At this time, the MMT packet generating apparatus according to the present invention generates the MPU by encapsulating the AU provided from the media codec layer (S200), and generates the MMT packet by packetizing the generated MPU (S210). In this case, the MMT packet generating apparatus selectively uses the sequence number in order to selectively perform packet error classification of multiple packet streams multiplexed on the same port. In other words, the MMT packet generating apparatus according to the present invention can selectively perform packet error classification of multiple packet streams multiplexed on the same port based on at least one of a substream sequence number and a general sequence number. Create

In some cases, the MMT packet generating apparatus may generate an MMT packet including various kinds of sequence numbers. Specifically, the selective use of the sequence number used by the MMT packet generating apparatus according to the present invention includes 1) using both the substream sequence number and the general sequence number by default, 2) the selective use of the substream sequence number, and the general sequence. Basic use of numbers, 3) basic use of substream sequence numbers, optional use of generic sequence numbers, or 4) use of only substream sequence numbers. Prior to S210, the MMT packet generation device may determine the sequence mode. In other words, the MMT packet generating apparatus may determine any one of the methods 1) to 4) as the sequence mode.

Table 1

Table 1 shows an MMT packet header structure according to an embodiment of the present invention. Table 1 shows a case in which both a substream sequence number and a general sequence number are basically used. By using both the substream sequence number and the general sequence number by default, for example, packet reordering and packet error processing are performed in units of multiplexed entire streams. Can be used if you need to always check if you belong.

Referring to Table 1, a header field of an MMT packet may include a generic_seqno field, a substream_ID field, and a substream_seqno field.

The generic_seqno field is a generic sequence number that is incremented by 1 for each packet in the order in which the packets are sent for the packet stream sent to the same port. The generic_seqno field may be called a packet_counter field. Same as below.

The substream_ID field is an identifier for distinguishing these individual streams from each other when multiplexing (sub) streams having different characteristics into one packet string. The substream_ID field may be called a packet_id field. Same as below.

The substream_seqno field indicates a subframe sequence number that increases by 1 for every packet for a packet stream having the same substream_ID. By using this, an operation based on a packet sequence number, such as error checking and error recovery, may be performed in units of substreams. That is, error control may be performed in units of subframes using the substream_seqno field included in the header field of the MMT packet received by the MMT packet receiver. The substream_seqno field may be called a packet_sequence_number field. Same as below.

TABLE 2

Table 2 shows an MMT packet header structure according to another embodiment of the present invention. Table 2 shows a case in which a substream sequence number is selectively used and a general sequence number is basically used. The substream sequence number is optionally used and the general sequence number is used by default. For example, packet order reordering and packet error processing are performed in units of multiplexed entire streams, but lost packets belong to any substream. It can be used to check whether or not to selectively perform according to the application.

Referring to Table 2, the header field of the MMT packet may include a generic_seqno field, a substream_ID field, a flag_substream_seqno field, and a substream_seqno field.

The generic_seqno field is a generic sequence number that is incremented by 1 for each packet in the order in which the packets are sent for the packet stream sent to the same port.

The substream_ID field is an identifier for distinguishing these individual streams from each other when multiplexing (sub) streams having different characteristics into one packet string.

The flag_substream_seqno field indicates whether the substream_seqno field exists in the header field. For example, when the flag_substream_seqno field has a value of 1, it may represent that the substream_seqno field exists in the header field. The flag_substream_seqno field may be called a packet_sequence_number_flag field. Same as below.

The substream_seqno field indicates a subframe sequence number that increases by 1 for every packet for a packet stream having the same substream_ID. By using this, an operation based on a packet sequence number, such as error checking and error recovery, may be performed in units of substreams.

TABLE 3

Table 3 shows an MMT packet header structure according to another embodiment of the present invention. Table 3 shows a case in which the substream sequence number is basically used and the general sequence number is selectively used. The substream sequence number is basically used, and the general sequence number is selectively used. For example, the packet error processing function or the reordering function is performed in the substream unit at the receiving side. Can only be used when using the full sequence number.

Referring to Table 3, a header field of an MMT packet may include a substream_seqno field, a substream_ID field, a flag_generic_seqno field, and a generic_seqno field.

The flag_generic_seqno field indicates whether the generic_seqno field exists in the header field. For example, if the flag_generic_seqno field has a value of 1, this may indicate that the generic_seqno field exists in the header field. The flag_generic_seqno field may be called a packet_counter_flag field. Same as below.

Table 4

Table 4 shows an MMT packet header structure according to another embodiment of the present invention. Table 4 shows a case where only the substream sequence number is used. The method of using only the service trim sequence number is, for example, a substream is demultiplexed at the receiving side, and basically, whether a lost packet is found for each substream, and at the same time, a single substream without multiplexing This is the case where the function of the existing general sequence number can be replaced by the substream sequence number.

Referring to Table 4, the header field of the MMT packet may include a substream_ID field and a substream_seqno field.

Referring to FIGS. 3 and 4, when three substreams having different substream_IDs are multiplexed and transmitted to one port, if the substream_seqno field is used, even if a packet loss occurs, the lost packet is originally received at the receiving end. It is possible to determine which substream it belongs to before being multiplexed. Therefore, when using the substream_seqno field together with the substream_ID field, different ARQ policies or error handling procedures may be taken for each substream.

In FIG. 3 and FIG. 4, substream A (substream_id = 1) contains, for example, time delay sensitive data, and in this case, an ARQ policy having a time limit may be used. Substream B (substream_id = 2) contains data such as, for example, a file which is not sensitive to time delay but should not have packet errors. In this case, a packet error recovery policy having no time limit can be used independently. . Substream C (substream_id = 3) contains relatively insignificant data, for example, so that complexity may be reduced by not taking a packet error policy. According to the present invention, there is an advantage in that different ARQ and error control policies can be individually taken for each subframe using the substream_ID field and the substream_seqno field as in the above-described examples.

5 is a block diagram illustrating an apparatus for generating an MMT packet according to the present invention. Referring to FIG. 5, the MMT packet generating apparatus 500 according to the present invention may include an encapsulation unit 510, a packetization unit 520, and a determination unit 530.

The encapsulator 510 generates an MPU by encapsulating the AU, and the packetizer 520 generates an MMT packet by packetizing the generated MPU. For example, the packetizer 520 may generate an MMT asset based on the MPU, and generate an MMT packet based on the MMT asset. The generated MMT packet may include the packet header structure of any one of Tables 1 to 4 described above.

The MMT packet generated by the packetizer 520 may then be transmitted from the transmitter to the receiver through the network. In this case, each stream for a plurality of MMT packets may be multiplexed and transmitted to one port. Accordingly, a substream may be substreamed based on a substream sequence number and / or a general sequence number included in a header of each MMT packet. Different ARQ policies or error control policies can be taken.

Also, the determiner 530 may determine whether to generate an MMT packet based on at least one of a substream sequence number and a general sequence number. In addition, the determination unit 530 may determine whether the substream sequence number or the general sequence number is basically included in the MMT packet or optionally.

Determining unit 530 is 1) using both the substream sequence number and the general sequence number by default, 2) optional use of the substream sequence number, the basic use of the general sequence number, 3) the basic use of the substream sequence number, Optional use of a generic sequence number, or 4) only the substream sequence number can be used to determine whether to construct a header. The determination unit 510 may determine any one of 1) to 4) in consideration of a time delay or a sensitivity regarding data loss.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims

In the MMT (MPEG Media Transport) packet generation device,

An encapsulation unit for generating an MPU by encapsulating the AU provided from the media codec layer; And

A packetizer configured to generate the MMT packet by packetizing the generated MPU,

And the packetizer generates the MMT packet having a packet header including a substream sequence number.
The method of claim 1,

The packetization unit generates the MMT packet, characterized in that for generating the MMT packet having a packet header further comprises a basic sequence number or selectively.
The method of claim 2,

And the packetizer generates the MMT packet having the packet header basically including both the subframe sequence number and the general sequence number.
The method of claim 2,

And the packetizer generates the MMT packet having the packet header selectively including the subframe sequence number and basically including the general sequence number.
The method of claim 2,

And the packetizer generates the MMT packet having the packet header including the subframe sequence number basically and optionally including the general sequence number.
In the MMT packet generating method by the MMT packet generating apparatus,

Encapsulating the AU provided from the media codec layer to generate an MPU; And

Generating an MMT packet by packetizing the generated MPU,

Wherein the MMT packet has a packet header including a substream sequence number.
The method of claim 6,

The MMT packet generating apparatus, characterized in that having a packet header further comprises a basic sequence number or optionally.
The method of claim 7, wherein

The packet header of the MMT packet, characterized in that basically includes both the subframe sequence number and the general sequence number, MMT packet generation method.
The method of claim 7, wherein

The packet header of the MMT packet optionally includes the subframe sequence number and basically includes the general sequence number.
The method of claim 7, wherein

The packet header of the MMT packet basically includes the subframe sequence number, and optionally includes the general sequence number.
As the header structure of an MMT packet,

Includes a substream ID field and a substream sequence number field by default,

And a general sequence number flag field indicating presence or absence of a general sequence number field.
The method of claim 11,

And optionally including the generic sequence number field based on the generic sequence number flag.